داریوش داوودی

The occurrence of inter-specific hybrids between two species in nature has the potential ability to develop new fruit trees with desirable traits. In this study, flower morphology, viability, and in vitro germination of pollen grains and self-(in) compatibility, using fruit set (%) and fluorescence microscopy methods were examined in three promising natural Prunus interspecific hybrids [P. armeniaca × P. salicina (Bavanat) and P. cerasifera × P. armeniaca (Shiraz and Shahriar)]. Bavanat and Shiraz had the highest flower diameter, while the highest number and length of stamens, as well as stamen number/pistil length ratio, belonged to Shahriar. The highest and lowest pollen viability and in vitro germination were observed in Shahriar and Bavanat, respectively. In general, sucrose concentrations of 150 to 250 g/l increased in vitro pollen germination rate, although concentrations of more than 150 g/l had a negative effect on Bavanat. The three-year average (2018-2020) of final fruit set by self-pollination ranged from 0% in Shiraz to 1.3% in Shahriar. A strong positive correlation was found between the occurrence of twin pistils and the mean temperature from July-August in the previous year. According to field self-pollination and fluorescent microscopy, all three genotypes were considered self-incompatible and needed pollinizer varieties.

Apricot is one of the most economically important fruit trees in temperate regions of Iran and in the world. However, it usually produces low fruit yield, due to its self-incompatibility. In this study, self-incompatibility status and flowering phenological characteristics of 19 five-years-old apricot genotypes, developed from open-pollination of Iranian commercial apricot cultivars; Shahroudi and Shams as female parents, and Italian cultivars; San Castrese, Palumella, Vitillo and Cafona as male parents, were evaluated. Timing of blooming, blooming duration, pollen germination (%), fruit set (%), timing of fruit ripening and some other traits were evaluated and recorded. The results showed that apricot genotypes were significantly different for timing of flowering, pollen germination (%), fruit formation (%) and timing of fruit ripening. Mean comparison showed that the highest pollen germination (%) belonged to genotype 525 (69%) and the lowest to genotype 579 (5.2%). Evaluation of data from controlled pollination and fluorescent microscopy study showed that 13 genotypes 431, 446, 432, 446, 451, 526, 546, 557, 565, 570, 576, 579 and 585 could be considered as self-compatible genotypes. Correlation coefficients showed that there was negative and highly significant relationship (r = -0.63**) in first year and (r = -0.48**) in second year, between timing of flowering and fruit ripening. Also correlation coefficient between pollen germination (%) and initial fruit set (%) was positive and highly significant (r = 0.97**). The results of this study implied that self-compatibility is easily transferred from parents to progenies, and the two identified late flowering genotypes can be used in apricot breeding programs.

Sugarcane is a monocotyledonous crop that is cultivated in the tropical and subtropical regions of the world. One of the most important criteria, influencing the efficiency of the sugarcane transformation is known to be related to physical and biological factors during the transformation procedure..

The objective of this research was to study the response of callus induction and embryogenic callus production and to identify the major parameters controlling DNA delivery by particle bombardment into sugarcane (Saccharum officinarum L.) cv. NCo310..

For callus induction and embryogenic callus production, leaf base segments were subjected to in vitro culture medium supplemented with two plant growth regulators (2,4-D and Dicamba). Results showed that 1 mg.L -1 2,4-D was significantly influential in callus induction and embryogenic callus production. Considering both physical and biological factors, the efficiency of DNA (uidA gene) delivery was assessed by scoring transient GUS (gene (β-glucuronidase)) expression in bombarded tissues..

The highest transient GUS expression was obtained when callus was bombarded with the construct harboring rice Act1 promoter, and having 9 cm target distance, 25 inHg vacuum pressure, 1 µm gold particles, 12.5 µg DNA per bombardment and one day pre-culture prior to the bombardment..

A bombardment procedure suitable for elite sugarcane varieties was developed, which allowed high-efficiency DNA delivery combined with reduced damage to target tissues..

Classical cytological studies were carried out to give karyological information about five hybrid cultivars of sugarcane. Root tips pretreated with saturated α-bromonaphthalene solution for 8 h at 4 °C. The roots were fixed in 1:1 chromic acid 1%: formaldehyde 10% for 48 h, followed by hydrolysis in 1N NaOH for 15 min at 60 °C. After enzymatic digestion of Hematoxylin-stained roots, each root tip was squashed in a drop of 45% acetic acid. Karyotype analysis showed that chromosome size varied from 0.571 μm to 5.076 μm with predominance of m chromosome types so that more than 50 paired chromosomes were m type in each cultivar. Multivariate tests of significance and ANOVA showed that, except for TF%, the means of Symmetry Index, Dispersion Index, Difference of Range of Relative Length, Coefficient of Variation, and Haploid Set Length were significantly different among cultivars. The karyotypes were similar with respect to TF%-based symmetry and centromere position of more than 90% of the chromosome pairs. These results showed apparently, that the evolution of karyotype in S. officinarum has mainly involved chromosome number and polyploidy rather than chromosomal changes and karyotype asymmetry